Devices and methods for temporary mounting of parts to bone

ABSTRACT

Devices and methods for temporarily affixing a surgical apparatus to a bony structure. The temporary mount includes a base member having a top face configured to be impacted by an insertion device and a plurality of elongated prongs extending downwardly from the base member and configured to engage a bony structure. The prongs are separated a distance from one another, and the prongs are configured to move inwardly toward one another when driven downward into the bony structure.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation of U.S. patent applicationSer. No. 14/824,586, filed on Aug. 12, 2015, the contents of which areincorporated herein in their entirety by reference for all purposes.

FIELD OF THE INVENTION

The present disclosure generally relates to devices and methods totemporarily mount an apparatus to bone. For example, these temporarymounts may be suitable for attaching an apparatus, such as a trackablereference array, to a bony structure in a patient's body to provide areference point during surgical navigation.

BACKGROUND OF THE INVENTION

During surgery, it may be necessary to temporarily mount an apparatus toexposed bone. For example, when using surgical navigation, it may benecessary to attach a tracker, such as a trackable reference array ofoptical markers, to the patient for accurately tracking the position oftools relative to the surgical site. If bone is the surgical target,such as when inserting a bone screw or the like, then attaching thereference array to bone provides better accuracy than attaching thereference array to surrounding soft tissues and more accurately tracksthe position of the surgical tools relative to the bone. After thesurgical procedure is completed (e.g., installing bone screws, rods,implants, and the like), the mounted tracker is typically removed.

Current methods for temporarily attaching trackers, reference arrays, orother devices to bone may include one or more of the following:screw-based mounting devices, in which one or more screws are insertedto hold the device to bone; clamp-based mounting devices, in which teethand jaws of a clamp or clamps are tightened around bony prominences; orspike-based devices, in which one or more spikes are driven into bonewith a mallet. These devices, however, may only provide for a singlepoint of fixation to the bone, thereby providing a weak attachment tothe bone and potentially compromising the accuracy of the tracker. Inaddition, traditional devices may be accidentally advanced too far intothe bony structure, which can damage the bone or surrounding areas ormake it difficult to remove the temporary mounting device, which isembedded too deeply into the bone, after the procedure is completed.

SUMMARY OF THE INVENTION

To meet this and other needs, devices, systems, kits, and methods fortemporarily mounting an apparatus, such as a tracker, to bony structuresare provided. In particular, the temporary devices may provide formultiple points of fixation to the bone, thereby providing a strongattachment to the bone and improving the accuracy of an attachedapparatus, such as a tracker for surgical navigation. The temporarymounting devices may also include features, such as stops includingprotrusions and arched regions, for example, which prevent the temporarymounting device from accidentally being advanced too far into the bonystructure. The design of the temporary mounts can help to protect thebone and surrounding areas and can be easier to remove from the bonewhen the surgical navigation and/or surgical procedure are completed.

According to one embodiment, a mount for temporarily affixing a surgicalapparatus to a bony structure (e.g., one or more vertebrae of a spine)includes a base member having a top face configured to be impacted by aninsertion device, and a plurality of elongated prongs extendingdownwardly from the base member and configured to engage a bonystructure. Each of the plurality of prongs are separated a distance fromone another. The prongs may be configured to move inwardly toward oneanother when driven downward into the bony structure by the insertiondevice. The mount has multiple points of fixation with the bonystructure to provide a strong and reliable attachment to the bone. Forexample, the plurality of prongs may include two or more, three or more,or four or more prongs extending from the base member. The prongs may beelongated in the form of legs, tines, spikes, pins, or the like.

The temporary mount may include one or more of the following features,for example. Each of the plurality of prongs may include a protrusionextending therefrom configured to act as a stop to preventover-insertion of the mount in the bony structure. The protrusions maybe in the form of hill-shaped prominences positioned along the length ofthe prong (e.g., spaced apart from a distal most end). The plurality ofelongated prongs may extend a length greater than a length of the basemember (e.g., the prongs are longer than the base member portion of themount such that the height of the device is primarily due to the heightof the prongs). The plurality of elongated prongs may be in the form ofa first prong and a second prong, and a transition from the first prongto the second prong may be arched or curved to act as an ultimate stopto prevent over-insertion of the mount in the bony structure. An archedstop may be provided between each prong. The plurality of elongatedprongs may include a first prong, a second prong, a third prong, and afourth prong, where a first arched portion between the first prong andthe second prong has a first distance from the top face, and a secondarched portion from the second prong to the third prong has a seconddistance from the top face, the second distance being different fromthan the first distance. In particular, the second distance may begreater than the first distance or vice versa. The arched portions onopposite sides of the device may be the same or substantiallyequivalent. In some embodiments, the mount may also include an outersleeve having a hollow interior configured to engage an outer surface ofthe base member and/or a portion of one or more outer surfaces of theprongs. The outer sleeve may be configured to slide or rotate, forexample, in order to compress the prongs inwardly toward one another.Each of the plurality of prongs may have a textured inner surfaceconfigured to resist extraction from the bone. Each of the plurality ofprongs may have a sharpened distal-most tip configured to penetrate thebony structure. When the base member is impacted by the insertiondevice, the temporary mount may provide an audible sound, as each of theprongs is driven downward, and the frequency of the audible sound maychange indicating the relative position of the mount in the bone (e.g.,when the mount is fully seated in the bone structure). The mount isconfigured to hold and engage a portion of a trackable reference array,which may assist in surgical navigation, for example, with a surgicalrobot.

According to another embodiment, a kit may include a plurality oftemporary mounts of different sizes and different configurations. Inaddition, the kit may include one or more devices suitable for surgicalnavigation, for example, including a trackable array, and configured tobe attachable to the temporary mounts; one or more central shaftsconfigured to guide the mount through soft tissue and into contact withbone; one or more driving sleeves configured to apply a force to thedriving sleeve to cause the temporary mount to advance into the bone;one or more insertion devices, such as impact drivers, mallets, or thelike, configured to engage the mounts, the central shafts, and/or thedriving sleeves; one or more removal devices, such as slap hammers,slide hammers, or the like, configured to retrieve and extract thetemporary mounts from the bone; and other tools and devices, which maybe suitable for surgery.

According to another embodiment, a system for temporarily affixing asurgical apparatus to a bony structure includes at least one temporarymount and a least one tracking device, such as a trackable referencearray for surgical navigation. The temporary mount includes a basemember having a top face configured to be impacted by an insertiondevice, and a plurality of elongated prongs extending downwardly fromthe base member and configured to engage a bony structure, wherein eachof the plurality of prongs are separated a distance from one another,and wherein the prongs are configured to move inwardly toward oneanother, for example, when driven downward into the bony structure. Thetrackable reference array is connected to the base member of thetemporary mount, for example, at an opening in the top face of the basemember.

According to yet another embodiment, a method of temporarily affixing asurgical apparatus to a bony structure includes (a) inserting a centralshaft through soft tissue and into contact with bone; (b) inserting acannulated temporary mount over the central shaft and moving thetemporary mount downwardly and into contact with the bone, thecannulated temporary mount having a first end configured to be engagedby an insertion tool and a second end terminating as a plurality ofelongated prongs configured to engage bone, wherein each of theplurality of prongs are separated a distance from one another, andwherein the prongs are configured to move inwardly toward one anotherwhen driven downward into the bony structure; (c) optionally,positioning a driving sleeve over the central shaft and into contactwith the first end of the temporary mount; (d) applying a force to thetemporary mount to advance at least a portion of the prongs into thebone, optionally, by applying a force to the driving sleeve; and (e)optionally, removing the driving sleeve and the central shaft to leavethe temporary mount embedded in the bone. In one embodiment, thetemporary mount further includes an outer sleeve, and the methodadditionally comprises (f) optionally, rotating the outer sleeve inorder to compress the prongs inwardly toward one another to furthersecure the mount to the bone. The method may also include (g) attachinga portion of a trackable reference array for surgical navigation to thetemporary mount and/or (h) removing the temporary mount from the boneafter the surgical navigation is complete.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIGS. 1A-1E depict a temporary mounting apparatus including multipleprongs or tines configured to engage a bony structure according to oneembodiment;

FIG. 2 depicts a temporary mounting apparatus with multiple prongs ortines according to another embodiment;

FIGS. 3A-3B show a temporary mounting apparatus with prongs that arecompressible by an outer sleeve according to another embodiment;

FIGS. 4A-4B show a temporary mounting apparatus with prongs that arecompressible by an outer sleeve according to yet another embodiment;

FIGS. 5A-5C show a device suitable to help guide a temporary mountingapparatus into position in the bony structure, for example, whenpositioning the temporary mounting apparatus through deep layers of softtissue; and

FIG. 6 illustrates the components and a series of steps, which may beused to install a temporary mounting apparatus in the bone.

DETAILED DESCRIPTION

Embodiments of the disclosure are generally directed to devices,systems, kits, and methods for temporarily mounting an apparatus, suchas a tracker for surgical navigation, to bony structures. Specifically,the temporary mounts may include a plurality of prongs, legs, spikes,tines, or the like, extending from a base member, which provide formultiple points of fixation to the bony structure. The bony structuremay include any bones, bony segments, bony portions, bone joints, or thelike of a patient. For example, the bony structure may include areasfrom a bone from the spine, such as a vertebra, a hip bone, such as anilium, a leg bone, such as a femur, or a bone from an arm, such as adistal forearm bone or a proximal humerus, or any other bone in amammal. In an exemplary embodiment, the bony structure or bone includesone or more vertebrae in the spinal column of a human patient. Providingfor multiple points of fixation allows for a stronger attachment to thebone and may maintain or improve the positional accuracy of an attachedapparatus, such as a tracker for surgical navigation.

The temporary mounting devices may also include features, such as stops,for example, to prevent or minimize the occurrence of the temporarymounting device from being advanced too far into the bony structure. Oneor more features on the temporary mounting devices can also help toprotect the bone and surrounding areas and may make it easier for thesurgeon to remove the temporary mounting device from the bone when thesurgical navigation has been completed.

The embodiments of the disclosure and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting embodiments and examples that are described and/orillustrated in the accompanying drawings and detailed in the followingdescription. The features of one embodiment may be employed with otherembodiments as the skilled artisan would recognize, even if notexplicitly stated herein. Descriptions of well-known components andprocessing techniques may be omitted so as to not unnecessarily obscurethe embodiments of the disclosure. The examples used herein are intendedmerely to facilitate an understanding of ways in which the disclosuremay be practiced and to further enable those of skill in the art topractice the embodiments of the disclosure. Accordingly, the examplesand embodiments herein should not be construed as limiting the scope ofthe disclosure, which is defined solely by the appended claims andapplicable law. Moreover, it is noted that like reference numeralsrepresent similar features and structures throughout the several viewsof the drawings.

According to a first embodiment, a spike-based device may includemultiple prongs or tines extending from a rigid base. For example, amount for temporarily affixing a surgical apparatus to a bony structure(e.g., vertebrae of a spine) includes a base member having a top faceconfigured to be impacted by an insertion device, and a plurality ofelongated prongs extending downwardly from the base member andconfigured to engage a bony structure. Each of the plurality of prongsare separated a distance from one another. The prongs may be configuredto move inwardly toward one another, for example, when driven downwardinto the bony structure or thereafter. The mount has multiple points offixation with the bony structure to provide a strong and reliableattachment to the bone. This device has several unique features thatgive it advantages when used to temporarily attach a reference array orother device to bone.

Referring now to the drawing, FIGS. 1A-1E depict a temporary mountingapparatus 10 including multiple prongs 20 configured to engage a bonystructure 18. Turning to FIG. 1A, a perspective view of the temporarymounting apparatus 10 is shown, which includes a base member 12 with aplurality of prongs 20 extending downwardly therefrom. The base member12 preferably forms a rigid base or frame for the mounting apparatus 10.The top face 14 of the base member 12 may connect with one or moreadjoining side faces (e.g., in this case, four adjoining side faces).For example, the base member 12 may form a partially cube-shaped orrectangular-shaped block. Although four sides are depicted, the basemember 12 may include more or less sides. Thus, the top face 14, whenviewed from above, may be substantially square shaped (e.g., all of thesides are of equal size), rectangular-shaped (e.g., two of the sides areof equal size), or of any other suitable shape. Each of the adjoiningside faces may form a corner edge therebetween. Each of the corner edgesmay be sharp, beveled, rounded, or the like.

The base member 12 may have a top face 14 configured to receiveimpaction forces from an insertion tool, such as an impact driver,mallet, or the like. The top face 14 may be substantially flat, curved,angled, for example, or of other suitable shape or contour. In anexemplary embodiment, the top face 14 of the device 10 is flat and canbe a suitable surface to strike the device 10 with an impact driver ormallet, for example. The top face 14 of the base member 12 may includean opening or aperture 16. The aperture 16 extends partially orcompletely through the base member 12. When extending completelytherethrough, the aperture 16 may provide for a cannulated device 10.The aperture 16 may be sized and dimensioned to receive, for example, aguide wire, post, or central shaft, discussed in more detail herein, toinsert the device 10 in a minimally invasive surgical procedure. Forexample, a post can be previously mounted to the spike 10, extendingupward therefrom, before the device 10 is driven into bone 18. Thedevice 10 can be driven by striking this post, which may be easier thanstriking the flat part shown, especially when driving the spike 10 downthrough regions surrounded by thick tissues.

After the mount 10 is in place seated in bone 18, attachments can bemounted to a portion of the device 10 in various ways. In particular,the hole or aperture 16 may also be sized and dimensioned to removablyconnect a portion of a tracker (not shown), such as a trackablereference array of optical markers, for surgical navigation and/orrobotic systems. Surgical navigation systems and trackable markers aredescribed in more detail in U.S. Pat. Nos. 8,010,181, 8,219,177,8,219,178, 9,078,685, and U.S. Publication Nos. 2013/0345718,2014/0275955, 2014/0378999, 2015/0032164, which are incorporated byreference herein in their entireties for all purposes. The aperture 16may be non-threaded, partially threaded, or fully threaded along itslength, for example. If the aperture 16 is threaded, a separate devicemounted to or having a bolt or shaft can be attached. Alternately, akeyed slot, snap-on attachment, clamp, or other means can be used toattach other devices, such as the reference array, to the device 10.

As shown in FIG. 1A, a plurality of prongs 20 extend from the basemember 12. The prongs 20 may be configured to penetrate and temporarilyengage bone 18, for example, as shown in FIG. 1E. In particular, theprongs 20 may be configured to secure the mount 10 to the bone 18 forthe duration of the surgical procedure and may be configured to beremoved from the bone 18 once the surgical operation is complete. Thus,the mounts 10 are not intended to be permanently affixed to the bone 18.The plurality of prongs 20 may include two or more, three or more, fouror more prongs, five or more prongs, or six or more prongs, for example.The prongs 20 may be in the form of tines, legs, spikes, pins, or thelike. The plurality of prongs 20 are preferably elongated such that theyhave a length substantially greater than their width. The prongs 20 mayhave a length or height greater than the length or height of the basemember 12 (e.g., about twice the height of the height of the base member12). Thus, the prongs 20 may make up a substantial portion of the heightof the device 10. Each of the prongs 20 may terminate at a distal endconfigured to penetrate the bony structure 18. In one embodiment, theprongs 20 are in the form of tines having sharp distal ends. It is alsoenvisioned, however, that the prongs 20 may have blunt, chamfered, orbeveled distal ends depending on the design of the prongs 20.

In one embodiment, four separate prongs 20 may be projecting from eachcorner of a cubic base member 12 and extending generally away from thetop face 14. With continued reference to FIG. 1A, the four prongs 20 mayinclude a first tine 22 extending downwardly from a first corner of thebase member 12, a second tine 24 extending downwardly from a secondcorner of the base member 12, a third tine 26 extending downwardly froma third corner of the base member 12, and a fourth tine 28 extendingdownwardly from a fourth corner of the base member 12. Thus, thetemporary mounting apparatus 10 may be in the form of a 4-pronged spike.Although four tines 22, 24, 26, 28 will be described in more detailherein with reference to the temporary mounting apparatus 10, it isenvisioned that the position and configuration of the tines may bevaried or changed as would be appreciated by one of ordinary skill inthe art.

With further reference to FIG. 1A, the tines 22, 24, 26, 28 extenddownwardly from the base member 12 at each respective corner. Eachcorner edge from the base member 12 extends continuously along eachrespective tine 22, 24, 26, 28. Thus, a plurality of sharp edges extendfrom a first end (e.g., the top face 14 configured to receive impactionfrom an insertion tool) of the device 10 to a second end (e.g., thedistal ends of the tines 22, 24, 26, 28 configured to penetrate andengage the bone 18). Each of tines 22, 24, 26, 28, when viewed from oneof the sides, may be tapered such that it has a wider section proximateto the base member 12 and progressive narrows toward its distal end. Theprongs 20 of the spike 10 may be intentionally designed thin enough thatthey plastically deform or curl while the device 10 is driven into bone18. This curling can lead to improved strength and rigidity of fixationbecause the prongs 20 become intertwined with the bone 18.

The device 10 may be constructed from a single piece of suitably strongand rigid material. The material is preferably biocompatible. Forexample, the material may include metals, such as stainless steel,titanium, or titanium alloys. Dimensions of the device 10 may be about10 mm×15 mm×60 mm but could be smaller or larger as needed depending onthe bone and application.

As best seen in the side view in FIG. 1B, a pair of prongs 20(representing each pair of tines 22, 24, 26, 28 from each respectiveside view) are separated a distance from one another. The prongs 20 maybe slightly inwardly angled. The amount of lateral spreading orsqueezing force that can be generated by the prongs 20 as the device 10is driven downward into the bone 18 can be influenced by the design ofthe taper of the four prongs 20, for example. When driven verticallydownward, the prongs 20 move toward each other as depicted by the arrowsin FIG. 1B. Depending on the circumstance, it may be desirable to havethe prongs 20 move toward each other, away from each other, or remainunchanged. In an exemplary embodiment, the prongs 20 are configured tomove inwardly toward one another when driven downward into the bonystructure or thereafter in order to provide a strong and reliableattachment to the bone 18.

Another feature of the 4-prong spike 10 is that the narrow and elongatedprongs 20 tend to ring musically. In other words, when device 10 isstruck by the impact driver or mallet, the device emits a frequency oraudible sound wave. The audible sensation of a frequency is commonlyreferred to as the pitch of a sound. A high pitch sound corresponds to ahigh frequency sound wave and a low pitch sound corresponds to a lowfrequency sound wave. Most people are capable of detecting a differencein frequency between two separate sounds, and thus, different pitches.As each prong 20 is driven downward and becomes encased more and more inthe bone 18, the frequency of the ringing noise, as the device 10 isstruck with the mallet, for example, changes. For example, as the devicebegins to enter the bone 18, the frequency may provide a lower pitch. Asthe device 10 becomes more encased in the bone 18, however, thefrequency changes to provide a higher pitch. This ringing quality canact as a feedback mechanism to let the surgeon know the position ordepth of the device 10 in the bone 18. Moreover, a higher pitch may letthe surgeon know that the device 10 is fully and rigidly seated in thebone 18.

As best seen in the close up view of the prong 20 (e.g., representingeach of the tines 22, 24, 26, 28) in FIG. 1C, the prong 20 may have aprotrusion 30, such as a hill-shaped protrusion or hill-shapedprominence, positioned along a length of the prong 20. For example, theprotrusion 30 may be positioned about half-way between the distal end ofthe prong 20 and where the prong 20 extends from the base member 12.These protrusions may be positioned at the same location or differentlocations along each of the prongs 20. In one embodiment, thehill-shaped prominence 30 is roughly 10-20 mm from the distal tips ofthe prongs 20. The protrusions 30 may face substantially inwardly towarda central cavity defined by the prongs 20. For example, the protrusion30 on the first tine 22 may face a similar protrusion 30 on the secondtine 24. Similar, protrusion 30 on the fourth tine 28 may face a similarprotrusion 30 on the third tine 26. Although only a single protrusion 30is depicted on each prong 20, each prong 20 may include more or lessprotrusions along their lengths and at varied positions along theirlengths.

These prominences or protrusions 30 are configured, at least in part, toact as a stop to prevent over-insertion of the device 10 into the bone18. As the device 10 is driven downward and when bone 18 reaches theseprominences or protrusions 30, the device 10 stops or slows. While it isstill possible to drive the device 10 beyond this point, more effort isneeded. Making these prominences or protrusions 30 as small hillsinstead of flat buttresses allows one or more of the prongs 20 tocontinue to be advanced if there is an irregularity of the bony surface18. Additionally, as the device 10 is driven downward, the wedgingaction of these prominences 30 against bone 18 increase the rigidity andholding strength.

As shown in the close up perspective view of the base member 12 in FIG.1D, transitions 32, 34 from one prong 20 to another act as ultimatestops. In particular, the transitions 32, 34 can be in the form ofarches, curves, arcs, catenaries, or the like. The arches or curves maybe normal or irregular in shape. The arched portions of the transitions32, 34 may have an apex substantially at a central point between twoadjacent prongs 20. In particular, arched transition 32 from the firsttine 22 to the second tine 24 has a first distance from the top face 14.The same arched transition 32, not visible in the views, is present fromthe third tine 26 to the fourth tine 28. Arched transition 34 from thesecond tine 24 to the third tine 26 has a second distance from the topface 14. The same arched transition 34 is present from the fourth tine28 to the first tine 22. The second distance to arched transitions 34 isgreater than the first distance to arched transitions. It is alsoenvisioned that the distances may be the same or different for each ofthe transitions 32, 34 between adjacent prongs 20.

When driven far enough to reach these stops or transitions 32, 34,further advancement of the device 10 is halted and device 10 cannot bedriven farther without considerable effort. These stops can be designedto be positioned to act as safety stops to prevent the user from drivingthe device 10 into unsafe regions, such as nerves or the spinal canal.The transitional regions of the device 10 are formed as arches insteadof corners because this design allows the prongs 20 to spread or squeezehorizontally (e.g., away from or toward one another) as the device 10 isdriven downward. Horizontal squeezing of the prongs 20 against theelastic resistance of the bending metal creates a compressive force onthe bone 18 between the prongs 20, thereby improving the rigidity of thedevice 10 and attachment to the bone 18. These transition portions 32,34 of the device 10 also can act as a prying point when the surgeon isready to remove the device 10. That is, a removal tool, such as ascrewdriver or similar tool, can be forced under these arched regions32, 34 and used to pry the device 10 upward to dislodge it from the bone18.

As best seen in FIG. 1E, the device 10 may be driven downward bystriking the top surface 14 or a post extending therefrom, for example,with a mallet (not shown). When correctly mounted, all four of the tines22, 24, 26, 28 are secured through the cortical shell and into thecancellous bone of a vertebral body. The four tines 22, 24, 26, 28, asopposed to one spike which is traditionally used, gives the device 10better holding strength than a single spike or nail because of the morenumerous penetration points in the bone 18 and the unique featuresdescribed herein.

According to another embodiment, FIG. 2 depicts a front view and a sideview of a temporary mounting apparatus 100 including a plurality ofprongs 120 extending downwardly from a base member 112 and a post 136extending upwardly therefrom. The top face 114 of the base member 112connects with four adjoining side faces having beveled or rounded edges.In this embodiment, the top face 114 is smaller in width than theremainder of the base member 112. The top face 114 is configured toreceive a fixed or removable post 136, for example, in an aperture (notshown) similar to aperture 16 described herein. For example, the post136 can be removably mounted to the base member 112, extending upwardtherefrom, before the device 100 is driven into bone 18. The spike 100can be driven by striking this post 136, which may be easier thanstriking the base member 112 directly, especially when driving thedevice 100 down through regions surrounded by thick tissues. In thisembodiment, the prongs 120 have also been modified such that the prongs120 have a wider cross section on one side than another. In addition,the hill-shaped prominences 130 have been elongated and positioned atdifferent locations along the length of the prongs 20.

According to yet another embodiment, FIGS. 3A-3B show a temporarymounting apparatus 200 with prongs 220 that are compressible by an outersleeve 238. In this embodiment, substantially parallel prongs 220 extendfrom base member 212. The base member 212 has a top face 214, whenviewed from above, that may be substantially round or oval in shape. Thebase member 212 and prongs 220 may form a substantially cylindricallyshaped device 200. The temporary mount 200 incorporates outer sleeve 238to facilitate compressing bone 18 between the prongs 220 of the device200. The outer sleeve 238 may be in the form of a nut, annular ring,collar, or the like having a central hollow portion extendingtherethrough and configured to receive a portion of the base member 212.The outer sleeve 238 may have a textured outer surface to facilitategripping and rotating the sleeve 238 about the device 200. The basemember 212 and a portion of the prongs 220 may be threaded to receivethe outer sleeve 238, and the sleeve 238 may have a corresponding innerthread (not visible in the drawing). The threaded portion of the basemember 212 may be of varying diameter (e.g., having a smaller diameterproximate the top face and a larger diameter proximate the prongs 220).As shown, distal portions of the outer surfaces of the prongs 220 may besubstantially smooth to improve penetration into the bone 18 and tolimit the amount of compression by the sleeve 238.

The top face 214 of the base member 212 may include an opening oraperture 216, which extends partially or completely through the basemember 212. Thus, the device 200 may be fully cannulated. The aperture16 may be sized and dimensioned to receive, for example, a guide wire,post, or central shaft for guiding the device 200 and/or may be sizedand dimensioned to removably connect to a portion of a tracker, such asa trackable reference array, for a surgical navigation system.

Similar to devices 10 and 100, the device 200 could initially bemalleted into place. Subsequently, the outer sleeve 238 would beactivated, for example by sliding or rotating the outer sleeve 238, tomove the outer sleeve 238 in a first direction toward the prongs 20, inorder to compress the prongs 220 inwardly toward one another. When thetemporary mounting apparatus 200 is to be removed, the outer sleeve 238could be slid or rotated to move the outer sleeve 238 in a seconddirection, opposite the first direction and away from the prongs, inorder to release the prongs 220. Such a mechanism might be especiallyuseful if the prongs 220 are forced down over a bony prominence, such asthe spinous process, and then need to be secured further by compressingand clamping the bone 18 between the prongs 220. As can be seen in FIGS.3A and 3B, one version of this design has the inner portion of thesleeve 238 threaded so that when the outer nut or sleeve 238 is rotatedand advanced downward toward the prongs 220, the prongs 220 of thedevice 200, if initially splayed outward, are forced inward to thediameter of the nut or sleeve 238.

Similar to device 200, FIGS. 4A-4B depict a temporary mounting apparatus300 with prongs 320 that have a sleeve 338 that is advanced by downwardforce or a threaded mechanism, and then locked in a compressed positionwith a half-turn mechanism. The prongs 320 may have outcroppings so thatwhen the outer sleeve or nut 338 is advanced over the prongs 320, theyare forced inward instead of just to the diameter of the nut 338. Asshown in FIG. 4A, an inner surface 321 of the prongs 320 may protrude oroverhang the remainder of the prongs 320 to enhance the clamping orcompressing feature. Another feature of this design may include aknurled or otherwise textured inner surface 322 of the prongs 320, bestseen in FIG. 4B, which also resists extraction of the device.

Another embodiment, depicted in FIGS. 5A-5C, may be useful when placingthe temporary mount apparatus 10, 100, 200, 300 into bone 18 throughdeep layers of soft tissue such as skin, fat, and muscle. For example,when attaching a 4-prong spike (e.g., apparatus 10, 100, 200, or 300) tothe iliac crest in a large patient, the spike may need to penetratethrough several inches of soft tissue before reaching bone 18. If thedevices 10, 100, 200, 300, described herein, were to be used afterslicing a small starter hole through the soft tissue, the prongs 12,112, 212, 312 could snag on the soft tissue as it was advanceddownwardly well before the prongs 12, 112, 212, 312 start to engage bone18. By way of example, a central shaft 400 can first be inserted,followed by one of the devices 10 (configured with aperture 16 extendingthrough the device), 200 (configured with aperture 216 extending throughthe device), 100 or 300 (modified such that it is hollow or cannulatedcentrally). After the device 10, 100, 200, 300 is in place and inserteddesirably in the bone 18, then the central shaft 400 can be removed.

The first step may be to position the central shaft 400 next to bone 18.An example of such a central shaft 400 is shown in FIG. 5A. For example,it may be roughly 10-25 mm in diameter and 150-250 mm long. The shaft400 may have a tooth 402 on a distal tip that serves to help pin it tobone 18 without wandering along the bone surface. The tooth 402 may bepositioned centrally in line with a central longitudinal axis of thedevice 400. Alternatively, more than one tooth 402 may be positioned atan alternate position on the distal tip of the central shaft 400. Thesurgeon could use manual force or malleting to push the shaft 400downward through soft tissue until they felt it hit bone 18. The path ofentry could be established freehand or guided using navigation or arobot.

One benefit of using the central shaft 400 as the initial penetrator ofsoft tissue is that it can be used to gauge the size of the device 10,100, 200, 300 that will ultimately be needed. As shown in FIG. 5C,graduated markings 404 may be provided along the length of the shaft 400such that the markings 404 can be read at the level of the skin or atthe level of the desired attachment. Using these graduated markings 40,the surgeon may determine where the tracking array would ultimately belocated. Based on this location, the appropriate sized cannulated device10, 100, 200, 300 could be selected from a set of options. Thus, aplurality of different mounts 10, 100, 200, 300, for example, ofdifferent sizes and different configurations may be provided as kit.Such a kit may also include the central shaft 400 as well as other toolssuitable for the surgery, for example, including the attachablecomponents, such as tracking arrays and the like.

As depicted in FIG. 6, the steps of implanting device 10 with thecentral shaft 400 are shown. Although described with reference to mount10, it is understood that these steps would apply equally to the othercannulated devices 100, 200, and 300 described herein.

As shown in step (a1), once the distal tip of the shaft 400 is in placeagainst bone 18, the proximal end of the central shaft 400 could be heldin one of the surgeon's hands, left in place by friction, or held by anassistant or robot. As shown in step (b1) the cannulated temporary mount10 is advanced over the central shaft 400. As shown in step (c1), thepronged mount 10 comes down into contact with the bone 18. The centralshaft 400 and mount 10 can be designed so that the prongs 20 hug theshaft 400, preventing soft tissue from getting snagged between theprongs 20 and the shaft 400.

If the cannulated device 10 is longer than the central shaft 400, thenstriking the cannulated device 10 with a mallet would drive it into thebone 18 as described above for the device 10. After the device 10 is inplace the central shaft 400 could be left in place or retrieved with atool such as a threaded rod that is threaded into a socket in thecentral shaft 400 (not shown). It may not be desirable to leave thecentral shaft 400 in place. When left in place while striking thecannulated device 10, there would be a risk that once the device 10advanced past the point of the end of the central shaft 400, furthermalleting could undesirably force the central shaft 400 into the bone18. Instead, the dimensions of the device 10 may be such that thecentral shaft 400 is longer than the device 10.

Alternatively, a sleeve member 406 could be used in order to drive thedevice 10 down over the central shaft 400. The sleeve member 406 mayoptionally include a head portion. In the design of the driving sleeve406, the enlarged head may be larger in diameter than the rest of theshaft to serve as a larger surface area for striking the piece. As canbe seen in alternative step (a2), the shaft 400 is positioned with thedevice 10 in contact with the bone 18. In step (b2), the sleeve member406 is positioned over the central shaft 400 and into contact with thedevice 10. In step (c2), the surgeon would mallet the sleeve member 406,causing advancement of the spike 10. Then, the sleeve member 400 wouldbe removed as shown in step (d2). Subsequently, in step (e2), thecentral shaft 400 would be removed, and the device 10 would be leftembedded in the bone 18. These components may be added and removedone-by-one or together. The desired attachment such as a navigationarray could then be placed on and attached to the device 10 usingsuitable techniques known in the art.

After navigation is complete and/or after the surgical operation iscomplete, but before the patient is closed, the device 10, 100, 200, 300can be removed, for example, by pulling it out, prying it out, or usinga slap-hammer attached to the aperture 16, 216 or a threaded socket onthe device 10, 100, 200, 300. The device 10, 100, 200, 300 can besterilized for re-use. Alternately, the device 10, 100, 200, and 300 maybe used as a disposable part.

The designs for the mounts 10, 100, 200, 300 described herein haveadvantages over the existing methods of using a single nail or spearheadshaped device. In particular, there are multiple points of fixation(e.g., four points of fixation) through cortical and into cancellousbone instead of just a single point found in traditional nails and thelike. This plurality of fixation points provides for strong attachmentto the bone 18 and improved accuracy of an attached apparatus, such as atracker for surgical navigation. The prongs 20, 120, 220, 320 are alsodesigned to be delicate enough that they deform while they are driveninto bone 18 to improve the rigidity of fixation. The temporary mountingdevices 10, 100, 200, 300 may also include one or more stops such thatthere is less of a chance of accidentally advancing the device 10, 100,200, 300 too far into the bone than often occurs with a single nail orspearhead. Thus, the design of the temporary mounts 10, 100, 200, 300can help to protect the bone 18 and surrounding areas and can be easierto remove from the bone 18 when the surgical navigation and/or surgicalprocedure are completed.

Although the invention has been described in detail and with referenceto specific embodiments, it will be apparent to one skilled in the artthat various changes and modifications can be made without departingfrom the spirit and scope of the invention. Thus, it is intended thatthe invention covers the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents. It is expressly intended, for example, that all rangesbroadly recited in this document include within their scope all narrowerranges which fall within the broader ranges. It is also intended thatthe components of the various devices disclosed above may be combined ormodified in any suitable configuration.

What is claimed is:
 1. A method of temporarily affixing a temporarymount to a bony structure, comprising: inserting a central shaft throughsoft tissue and into contact with bone; inserting a cannulated temporarymount over the central shaft and moving the temporary mount downwardlyand into contact with the bony structure, the cannulated temporary mounthaving a first end and a second end terminating as a plurality ofelongated prongs, wherein each of the plurality of elongated prongs areseparated a distance from one another, and wherein the plurality ofelongated prongs are configured to move inwardly toward one another whendriven downward into the bony structure; positioning a driving sleeveover the central shaft and into contact with the first end of thetemporary mount; applying a force to the driving sleeve to cause thetemporary mount to advance into the bony structure; and removing thedriving sleeve and the central shaft to leave the temporary mountembedded in the bony structure.
 2. The method of claim 1, wherein thetemporary mount includes an outer sleeve, and the method furthercomprising rotating the outer sleeve in order to compress the pluralityof elongated prongs inwardly toward one another to further secure themount to the bony structure.
 3. The method of claim 1, furthercomprising: attaching a portion of a trackable reference array forsurgical navigation to the temporary mount.
 4. The method of claim 3,further comprising: removing the temporary mount from the bony structureafter the surgical navigation is complete.
 5. The method of claim 1,wherein the temporary mount has multiple points of fixation with thebony structure.
 6. The method of claim 1, wherein the plurality ofelongated prongs includes four or more prongs extending from a basemember.
 7. The method of claim 6, wherein the plurality of elongatedprongs extend a length greater than a length of the base member.
 8. Themethod of claim 6, wherein the plurality of elongated prongs include afirst prong, a second prong, a third prong, and a fourth prong, whereina first arched portion between the first prong and the second prong hasa first distance from a top face of the base member, and a second archedportion from the second prong to the third prong has a second distancefrom the top face, the second distance being greater than the firstdistance.
 9. The method of claim 6, further comprising: impacting thebase member is impacted with an insertion device to drive the elongatedprongs downward, wherein when the base member is impacted, the temporarymount provides an audible sound, and as each of the elongated prongs isdriven downward, a frequency of the audible sound changes indicatingwhen the temporary mount is fully seated in the bone structure.
 10. Themethod of claim 1, wherein each of the plurality of elongated prongsincludes a protrusion extending therefrom configured to act as a stop toprevent over-insertion of the temporary mount in the bony structure. 11.The method of claim 10, wherein each protrusion is a hill-shapedprominence.
 12. The method of claim 1, wherein the plurality ofelongated prongs includes a first prong and a second prong, and atransition from the first prong to the second prong is arched to providean ultimate stop to prevent over-insertion of the temporary mount in thebony structure.
 13. The method of claim 1, wherein each of the pluralityof elongated prongs have a textured inner surface configured to resistextraction from the bony structure.
 14. The method of claim 1, whereineach of the plurality of elongated prongs have a distal-most tipconfigured to penetrate the bony structure.
 15. The method of claim 1,wherein the temporary mount is configured to hold and engage a portionof a trackable reference array for surgical navigation.
 16. The methodof claim 1, wherein the bony structure is a vertebra of a spine.